Local Notification with Sound

Caution: 

1. Android in Debug Mode has no sound!!! in build mode has sound

2. For Android 8.0+, sounds and vibrations are associated with notification channels and can only be configured when they are first created. Showing/scheduling a notification will create a channel with the specified id if it doesn't exist already. If another notification specifies the same channel id but tries to specify another sound or vibration pattern then nothing occurs.

Custom sound path:

flutter_app_name > android > app > src > res > raw > slow_spring_board.mp3

 // Method 1

Future _showNotificationWithSound() async {
  var androidPlatformChannelSpecifics = new AndroidNotificationDetails(
      'your channel id', 'your channel name', 'your channel description',
      sound: 'slow_spring_board',
      importance: Importance.Max,
      priority: Priority.High);
  var iOSPlatformChannelSpecifics =
      new IOSNotificationDetails(sound: "slow_spring_board.aiff");
  var platformChannelSpecifics = new NotificationDetails(
      androidPlatformChannelSpecifics, iOSPlatformChannelSpecifics);
  await flutterLocalNotificationsPlugin.show(
    0,
    'New Post',
    'How to Show Notification in Flutter',
    platformChannelSpecifics,
    payload: 'Custom_Sound',
  );
}// Method 2
Future _showNotificationWithDefaultSound() async {
  var androidPlatformChannelSpecifics = new AndroidNotificationDetails(
      'your channel id', 'your channel name', 'your channel description',
      importance: Importance.Max, priority: Priority.High);
  var iOSPlatformChannelSpecifics = new IOSNotificationDetails();
  var platformChannelSpecifics = new NotificationDetails(
      androidPlatformChannelSpecifics, iOSPlatformChannelSpecifics);
  await flutterLocalNotificationsPlugin.show(
    0,
    'New Post',
    'How to Show Notification in Flutter',
    platformChannelSpecifics,
    payload: 'Default_Sound',
  );
}